Selection Of Resistant Mutants Research Articles

Immunovirological status in people with perinatal and adult-acquired HIV-1 infection: a multi-cohort analysis from France

No study has compared the virological and immunological status of young people with perinatally-acquired HIV infection (P-HIV) with that of people with HIV adulthood (A-HIV) having a similar duration of infection. 5 French cohorts of P-HIV and A-HIV patients with a known date of HIV-infection and receiving antiretroviral treatment (ART), were used to compare the following proportions of: virological failure (VF) defined as plasma HIV RNA ≥ 50 copies/mL, CD4 cell percentages and CD4:CD8 ratios, at the time of the most recent visit since 2012. The analysis was stratified on time since infection, and multivariate models were adjusted for demographics and treatment history. 310P-HIV were compared to 1515 A-HIV (median current ages 20.9 [IQR:14.4-25.5] and 45.9 [IQR:37.9-53.5] respectively). VF at the time of the most recent evaluation was significantly higher among P-HIV (22.6%, 69/306) than A-HIV (3.3%, 50/1514); p≤0.0001. The risk of VF was particularly high among the youngest children (2-5 years), adolescents (13-17 years) and young adults (18-24 years), compared to A-HIV with a similar duration of infection: adjusted Odds-Ratio (aOR) 7.0 [95% CI: 1.7; 30.0], 11.4 [4.2; 31.2] and 3.3 [1.0; 10.8] respectively. The level of CD4 cell percentages did not differ between P-HIV and A-HIV. P-HIV aged 6-12 and 13-17 were more likely than A-HIV to have a CD4:CD8 ratio ≥ 1: 84.1% vs. 58.8% (aOR=3.5 [1.5; 8.3]), and 60.9% vs. 54.7% (aOR=1.9 [0.9; 4.2]) respectively. P-HIV were at a higher risk of VF than A-HIV with a similar duration of infection, even after adjusting for treatment history, whereas they were not at a higher risk of immunological impairment. Exposure to viral replication among young patients living with HIV since birth or a very early age, probably because of lower adherence, could have an impact on health, raising major concerns about the selection of resistance mutations and the risk of HIV transmission. Inserm - ANRS MIE.

Phage treatment of Pseudomonas aeruginosa yields a phage-resistant population with different susceptibility to innate immune responses and mild effects on metabolic profiles

In this study, we have investigated innate immune activation capacity and metabolic features of a population of P. aeruginosa PAO1 phage-resistant mutants with diverse genetic modification (large genomic deletions and point mutations) arising after exposure to phages targetting lipopolysaccharide (LPS) or Type-4 pili (T4P). Deletions led to the loss of genes involved in LPS synthesis, cell envelope permeability, efflux systems, biofilm production, oxidative stress tolerance, and DNA repair. Loss of LPS O antigen resulted in bacterial sensitivity to serum complement and stimulation of inflammatory cascades but did not cause increased phagocytosis, while T4P phage-resistant mutants were more effectively phagocytized than LPS-defective mutants. Changes in the utilization of different carbon, nitrogen, sulphur, and phosphorus sources were identified, especially in mutants where the two phage DNA persisted in the bacterial population (pseudolysogeny). However, the metabolic changes did not directly correlate with single-gene mutations or the large gene deletions, suggesting they reflect adaptive changes to the gene modifications that arise during the selection of resistant mutants. In contrast, phage-resistant mutants were susceptible to humoral innate immune responses, suggesting that phage resistance may be a beneficial outcome of phage therapy.

Heteroresistance to colistin in wild-type Klebsiella pneumoniae isolates from clinical origin

ABSTRACT Heteroresistance to colistin can be defined as the presence of resistant subpopulations in an isolate that is susceptible to colistin. The aim of this work was to study heteroresistance in 10 wild-type Klebsiella pneumoniae isolates of clinical origin, to determine the importance of persisters variants and stable mutants in heteroresistance, and to describe genomic changes observed in mutants obtained in population analysis profiling (PAP) assays. Mutations in genes related to colistin resistance (including pmr A, pmr B, pmr C, pmr D, pho P, pho Q, crr A, ccr B, mgr B, ram A, rom A, lax A, lpx C, lpx D, acr A, and acr B) were investigated by whole-genome sequencing with an Illumina platform. Additionally, PCR and Sanger sequencing of the mgr B gene of the selected mutants were also performed. PAP showed that the investigated K. pneumoniae isolates present heteroresistance to colistin, which is related to both the growth of persisters variants and the selection of resistant mutants. A total of 31-point mutations were identified in proteins PhoP, PhoQ, PmrB, and CrrB of which novel mutations were reported in PhoP (E22K, L12Q, and M175K), PhoQ (V24G and L105Q), PmrB (G207D), and CrrB (G183V). MgrB changes included amino acid substitutions (D31N and L19R), deletions (∆C28, ∆C39, ∆Q22, and ∆W6) or the presence of insertion sequences belonging to the IS1 (ISKpn14) and IS5 (ISKpn74) families that inactivated the gene. The results of this study will help to understand the mechanisms involved in colistin heteroresistance among wild-type K. pneumoniae isolates. IMPORTANCE Colistin is one of the last remaining therapeutic options for dealing with Enterobacteriaceae. Unfortunately, heteroresistance to colistin is also rapidly increasing. We described the prevalence of colistin heteroresistance in a variety of wild-type strains of Klebsiella pneumoniae and the evolution of these strains with colistin heteroresistance to a resistant phenotype after colistin exposure and withdrawal. Resistant mutants were characterized at the molecular level, and numerous mutations in genes related to lipopolysaccharide formation were observed. In colistin-treated patients, the evolution of K. pneumoniae heteroresistance to resistance phenotype could lead to higher rates of therapeutic failure.

Tigecycline-Rifampicin Restrains Resistance Development in Carbapenem-Resistant Klebsiella pneumoniae.

The goal of this study was to clarify the synergistic antibacterial activity of the combination of tigecycline (TGC) and rifampicin (RIF). Additionally, the study sought to investigate the impact of this combination on the development of mutational resistance and to assess its efficacy in an in vivo model using Galleria mellonella. Through a checkerboard test, we found that the combination of TGC and RIF showed synergistic antibacterial activity against carbapenem-resistant Klebsiella pneumoniae (CRKP). The fractional inhibition concentration index (FICI) was found to be ≤0.5, confirming the potency of the combination. Additionally, this synergistic effect was further validated in vivo using the G. mellonella infection model. TGC-RIF treatment had a lower mutant prevention concentration (MPC) than that of monotherapy, indicating its potential to reduce the development of mutational resistance. We observed a substantial variation in the MPCs of TGC and RIF when they were measured at different proportions in the combinations. Furthermore, during the resistant mutant selection window (MSW) test, we noticed a correlation between strains with low FICI and low MSW. The expression of efflux-pump-related genes, namely rarA and acrB, is significantly decreased in the combination therapy group. This indicates that altered expression levels of certain efflux pump regulator genes are associated with a combined decrease in bacterial mutation resistance. In conclusion, the combination of TGC and RIF effectively suppresses antibiotic resistance selection in CRKP. This study establishes a paradigm for evaluating drug-resistant mutant suppression in antimicrobial combination therapy.

Intermittent antibiotic treatment of bacterial biofilms favors the rapid evolution of resistance

Bacterial antibiotic resistance is a global health concern of increasing importance and intensive study. Although biofilms are a common source of infections in clinical settings, little is known about the development of antibiotic resistance within biofilms. Here, we use experimental evolution to compare selection of resistance mutations in planktonic and biofilm Escherichia coli populations exposed to clinically relevant cycles of lethal treatment with the aminoglycoside amikacin. Consistently, mutations in sbmA, encoding an inner membrane peptide transporter, and fusA, encoding the essential elongation factor G, are rapidly selected in biofilms, but not in planktonic cells. This is due to a combination of enhanced mutation rate, increased adhesion capacity and protective biofilm-associated tolerance. These results show that the biofilm environment favors rapid evolution of resistance and provide new insights into the dynamic evolution of antibiotic resistance in biofilms.

Development of Enterovirus Antiviral Agents That Target the Viral 2C Protein.

The Enterovirus (EV) genus includes several important human and animal pathogens. EV-A71, EV-D68, poliovirus (PV), and coxsackievirus (CV) outbreaks have affected millions worldwide, causing a range of upper respiratory, skin, and neuromuscular diseases, including acute flaccid myelitis, and hand-foot-and-mouth disease. There are no FDA-approved antiviral therapeutics for these enteroviruses. This study describes novel antiviral compounds targeting the conserved non-structural viral protein 2C with low micromolar to nanomolar IC50 values. The selection of resistant mutants resulted in amino acid substitutions in the viral capsid protein, implying these compounds may play a role in inhibiting the interaction of 2C and the capsid protein. The assembly and encapsidation stages of the viral life cycle still need to be fully understood, and the inhibitors reported here could be useful probes in understanding these processes.

Rational Polypharmacological Targeting of FLT3, JAK2, ABL and ERK1 By Pluripotin Suppresses the Adaptive Resistance to FLT3 Inhibitors in AML

Background: Despite significant advancement in developing FLT3 inhibitors, treatment failure is common due to emergence of resistance. Most patients developed resistance within short duration even on continued TKI therapy. Both type-I (gilteritinib and crenolanib) and type-II (quizartinib and sorafenib) FLT3 inhibitors have been evaluated in patients. Regardless of their selectivity and mode of inhibition, resistance emerged. Nonetheless, mechanisms driving resistance partly differ between type-I and type-II inhibitors. For instance, resistance to type-II inhibitors is predominately mediated by the on-target selection of resistant mutations in the FLT3 kinase domain, while resistance to type-I inhibitors is principally driven by off-target activation of RAS-MAPK, BCR-ABL, JAK2/JAK1 signaling. A minority of resistant patients showed the emergence of mutations in genes regulating metabolism and transcription. However, its relevance in conferring resistance has not been evaluated. Besides, like other TKI treated malignancies, gatekeeper mutation (F691L) conferred resistance to both type-I and type-II FLT3 inhibitors and poses a significant clinical challenge. It is not clear why on-target acquired resistance is more frequent with type-II inhibitors in comparison to type-I inhibitors where adaptive resistance to compensatory signaling is more common. It is likely possible that stabilization of active kinase conformation by type-I inhibitor is, nonetheless, enzymatically active but its non-enzymatic function (signaling scaffold) drives the adaptation to alternate survival pathways. Nevertheless, these studies informed that FLT3 resistant variants could be suppressed by switching to next-generation FLT3 inhibitors or dose escalation as demonstrated in managing the TKI resistance in chronic myeloid leukemia (CML). However, unlike CML, resistance conferred by off-target activation of MAPKs, BCR-ABL, and JAKs in AML remains a serious challenge. Results: The persistence of residual disease is the root cause of resistance. Strategies aimed at greater front-line disease eradication and suppression of resistance are needed, most of which depends on further research into combination chemotherapy or to develop polypharmacological agents targeting FLT3, its resistant variants, BCR-ABL, JAK2, and MAPKs. To address this, we performed a cell-based screening to identify the small molecule inhibitor active against FLT3, BCR-ABL, JAK2, and MAPKs. Here we show that pluripotin (SC-1), an inhibitor of RASGAP, and MAPK3, potently inhibits the kinase activity of FLT3, BCR-ABL, and JAK2. Structural modeling studies revealed that it binds with inactive conformations of FLT3, JAK2, and ABL. It is an equipotent inhibitor to both FLT3ITD and its most vexing resistant variant, the gatekeeper mutant F691L. Consequently, it potently suppressed the leukemic progression of TKI resistant primary AML in a preclinical mouse model, FLT3ITD/ITD/Tet2-/- mice develop robust leukemia and are resistant to FLT3 TKIs, e.g., Quizartinib and Gilteritinib, Fig 1. As expected, pluripotin treatment efficiently suppressed the adaptive resistance conferred by MAPK, BCR-ABL, and JAK2 signaling. As a proof of concept, we provide evidence that unique polypharmacology of pluripotin targeting FLT3, BCR-ABL, JAK2, and MAPK efficiently suppressed the leukemic progression in multiple preclinical mouse models as well as in mice engrafted with primary AML cells. Conclusions: Our preclinical data suggest that up-front targeting of key signaling nodes driving adaptive resistance by polypharmacological agents provides durable response, which is not achieved by currently used FLT3 inhibitors. Altogether, these studies warrant clinical evaluation of pluripotin to suppress the adaptive resistance for durable response. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

A Literature Review on Recent Advancements in the Treatment of Human Immunodeficiency Virus

Abstract: The aim of this study is to conduct an extensive literature review on recent advancements in the treatment of human immunodeficiency virus (HIV). This is because in extant studies, the care of the HIV infected patient has changed dramatically in the last few years. Potent new antiretroviral drugs combined with updated treatment strategies have now achieved efficient inhibition of HIV replication in most patients. Classes of drugs include both nucleoside and non-nucleoside inhibitors of the viral enzyme reverse transcriptase (RT) and inhibitors of the viral protease and integrase enzymes. The methodology used in this study was reviewed from secondary sources of information including journals, articles, newspaper, and textbooks. In this study, authors found that a major drawback of the highly active antiretroviral therapy (HAART) is the selection of resistant mutants under suboptimal dosage, in advanced stages of disease or after pre-treatment with mono- or double-combination regimens. In addition, monitoring of antiretroviral therapy is achieved by measurement of viral load using nucleic acid amplification techniques. Strict adherence to HIV drug regimens was reported to be essential for reaching and maintaining therapeutic levels of anti-retro-virals and avoiding development of drug-resistant HIV strains. This strict dosage-taking adherence makes HIV therapies among the most challenging treatments with which to adhere. Future researchers are encouraged to adopt a scientific approach in investigating the various constructs that have emerged in this study in other to provide more generalized findings for the research community and public policy makers. Keywords: Antiretroviral Drugs: Combination Therapy: Medication: Transmission: Inhibitors: Immune System.

Nisin Mutant Prevention Concentration and the Role of Subinhibitory Concentrations on Resistance Development by Diabetic Foot Staphylococci.

The most prevalent microorganism in diabetic foot infections (DFI) is Staphylococcus aureus, an important multidrug-resistant pathogen. The antimicrobial peptide nisin is a promising compound for DFI treatment, being effective against S. aureus. However, to avoid the selection of resistant mutants, correct drug therapeutic doses must be established, being also important to understand if nisin subinhibitory concentrations (subMIC) can potentiate resistant genes transfer between clinical isolates or mutations in genes associated with nisin resistance. The mutant selection window (MSW) of nisin was determined for 23 DFI S. aureus isolates; a protocol aiming to prompt vanA horizontal transfer between enterococci to clinical S. aureus was performed; and nisin subMIC effect on resistance evolution was assessed through whole-genome sequencing (WGS) applied to isolates subjected to a MEGA-plate assay. MSW ranged from 5–360 μg/mL for two isolates, from 5–540 μg/mL for three isolates, and from 5–720 μg/mL for one isolate. In the presence of nisin subMIC values, no transconjugants were obtained, indicating that nisin does not seem to promote vanA transfer. Finally, WGS analysis showed that incubation in the presence of nisin subMIC did not promote the occurrence of significant mutations in genes related to nisin resistance, supporting nisin application to DFI treatment.

Mechanisms of antibiotic action shape the fitness landscapes of resistance mutations

Antibiotic-resistant pathogens are a major public health threat. A deeper understanding of how an antibiotic’s mechanism of action influences the emergence of resistance would aid in the design of new drugs and help to preserve the effectiveness of existing ones. To this end, we developed a model that links bacterial population dynamics with antibiotic-target binding kinetics. Our approach allows us to derive mechanistic insights on drug activity from population-scale experimental data and to quantify the interplay between drug mechanism and resistance selection. We find that both bacteriostatic and bactericidal agents can be equally effective at suppressing the selection of resistant mutants, but that key determinants of resistance selection are the relationships between the number of drug-inactivated targets within a cell and the rates of cellular growth and death. We also show that heterogeneous drug-target binding within a population enables resistant bacteria to evolve fitness-improving secondary mutations even when drug doses remain above the resistant strain’s minimum inhibitory concentration. Our work suggests that antibiotic doses beyond this “secondary mutation selection window” could safeguard against the emergence of high-fitness resistant strains during treatment.

Identification and characterization of a fungal-selective glutaminyl tRNA synthetase inhibitor with potent activity against Candida albicans

Candida albicans is the leading cause of systemic candidiasis. Effective treatment is threatened by a dearth of antifungal options and the emergence of resistance. Thus, there is an urgent need to identify novel therapeutic targets to expand our antifungal armamentarium. A promising approach is the discovery of essential genes, as most antimicrobials target essential bioprocesses. Despite detailed characterization of gene essentiality in Saccharomyces cerevisiae,defining essential targets in the pathogen of interest is necessary due to the high level of divergence between these organisms. Thus, using a machine learning algorithm we generated a comprehensive prediction of all genes essential in C. albicans. We leveraged our essentiality predictions with high-throughput screening and chemogenomic datasets to assign the mechanism of action of a previously uncharacterized compound. We identified T-035897 as a molecule with potent bioactivity against C. albicans. Prior chemogenomic profiling in S. cerevisiae suggested that T-035897 targets the glutaminyl tRNA synthetase Gln4, whose homolog in C. albicans was predicted and verified to be required for viability. To confirm the mechanism of T-035897 in C. albicans, we performed haploinsufficiency profiling,which supported Gln4as the target. In parallel, selection of resistant mutants and targeted sequencing uncovered substitutions in the Gln4 catalytic domain. Moreover, T-035897 inhibited translation in afluorescence-based reporter assay. Finally, T-035897 selectively abrogated fungal cell growth in a co-culture model with mammalian cells. Thus, we highlight the power of leveraging essentiality datasets in order to characterize compounds with potent antifungal activity in an effort to unveil novel therapeutic strategies.

Yeast Double Transporter Gene Deletion Library for Identification of Xenobiotic Carriers in Low or High Throughput.

ABSTRACTThe routes of uptake and efflux should be considered when developing new drugs so that they can effectively address their intracellular targets. As a general rule, drugs appear to enter cells via protein carriers that normally carry nutrients or metabolites. A previously developed pipeline that searched for drug transporters using Saccharomyces cerevisiae mutants carrying single-gene deletions identified import routes for most compounds tested. However, due to the redundancy of transporter functions, we propose that this methodology can be improved by utilizing double mutant strains in both low- and high-throughput screens. We constructed a library of over 14,000 strains harboring double deletions of genes encoding 122 nonessential plasma membrane transporters and performed low- and high-throughput screens identifying possible drug import routes for 23 compounds. In addition, the high-throughput assay enabled the identification of putative efflux routes for 21 compounds. Focusing on azole antifungals, we were able to identify the involvement of the myo-inositol transporter, Itr1p, in the uptake of these molecules and to confirm the role of Pdr5p in their export.

Efflux Pump Mediated Antimicrobial Resistance by Staphylococci in Health-Related Environments: Challenges and the Quest for Inhibition.

The increasing emergence of antimicrobial resistance in staphylococcal bacteria is a major health threat worldwide due to significant morbidity and mortality resulting from their associated hospital- or community-acquired infections. Dramatic decrease in the discovery of new antibiotics from the pharmaceutical industry coupled with increased use of sanitisers and disinfectants due to the ongoing COVID-19 pandemic can further aggravate the problem of antimicrobial resistance. Staphylococci utilise multiple mechanisms to circumvent the effects of antimicrobials. One of these resistance mechanisms is the export of antimicrobial agents through the activity of membrane-embedded multidrug efflux pump proteins. The use of efflux pump inhibitors in combination with currently approved antimicrobials is a promising strategy to potentiate their clinical efficacy against resistant strains of staphylococci, and simultaneously reduce the selection of resistant mutants. This review presents an overview of the current knowledge of staphylococcal efflux pumps, discusses their clinical impact, and summarises compounds found in the last decade from plant and synthetic origin that have the potential to be used as adjuvants to antibiotic therapy against multidrug resistant staphylococci. Critically, future high-resolution structures of staphylococcal efflux pumps could aid in design and development of safer, more target-specific and highly potent efflux pump inhibitors to progress into clinical use.

Activity of the combination of colistin and fosfomycin against NDM-1-producing Escherichia coli with variable levels of susceptibility to colistin and fosfomycin in a murine model of peritonitis.

Alternative treatments are needed against NDM-1-producing Escherichia coli. Colistin (COL) and fosfomycin (FOS) often remain active in vitro but selection of resistant mutants is frequent if used separately. We determined whether the combination of colistin and fosfomycin may be useful to treat infections with NDM-1-producing E. coli with varying levels of resistance. Isogenic derivatives of E. coli CFT073 with blaNDM-1 and variable levels of resistance to colistin and fosfomycin (CFT073-NDM1, CFT073-NDM1-COL and CFT073-NDM1-FOS, respectively) were used. The combination (colistin + fosfomycin) was tested in vitro and in a fatal peritonitis murine model. Mortality and bacterial loads were determined and resistant mutants detected. Colistin MICs were 0.5, 16 and 0.5 mg/L and fosfomycin MICs were 1, 1 and 32 mg/L against CFT073-NDM1, CFT073-NDM1-COL and CFT073-NDM1-FOS, respectively. In time-kill curves, combining colistin with fosfomycin was synergistic and bactericidal against CFT073-NDM1 and CFT073-NDM1-FOS, with concentrations of 4× MIC (for both drugs), but not against CFT073-NDM1-COL (concentrations of colistin = 0.5× MIC), due to regrowth with fosfomycin-resistant mutants. Mice died less and bacterial counts were lower in spleen with the combination compared with monotherapy against all strains; the combination prevented selection of resistant mutants except for CFT073-NDM1-COL where fosfomycin-resistant mutants were found in all mice. Combining colistin and fosfomycin was beneficial in vitro and in vivo against NDM-1-producing E. coli, even with strains less susceptible to colistin and fosfomycin. However, the combination failed to prevent the emergence of fosfomycin-resistant mutants against colistin-resistant strains. Combining colistin and fosfomycin constitutes an alternative for treatment of NDM-1 E. coli, except against colistin-resistant strains.

Ceftazidime-avibactam.

Ceftazidime is a 3rd generation cephalosporin active against Pseudomonas aeruginosa. Avibactam is an inhibitor of class A, C and some class D β-lactamases. The antibacterial spectrum of ceftazidime-avibactam covers 95% of P. aeruginosa isolates and >99% of enterobacteria, including strains carrying extended-spectrum β-lactamases (ESBLs). Selection of resistant mutants in Klebsiella pneumoniae and Enterobacter cloacae strains producing KPC-3 or KPC-2 after exposure to ceftazidime-avibactam has been described by the appearance of one or more amino acid changes in the Ω-loop of the β-lactamase. These strains usually regain susceptibility to meropenem. There is evidence of a shorter multidrug-resistant organisms colonization period in patients treated with this antimicrobial, which could be beneficial in the treatment of infections caused by bacteria carrying ESBLs or carbapenemases.

Mathematical Modeling of Remdesivir to Treat COVID-19: Can Dosing Be Optimized?

The antiviral remdesivir has been approved by regulatory bodies such as the European Medicines Agency (EMA) and the US Food and Drug administration (FDA) for the treatment of COVID-19. However, its efficacy is debated and toxicity concerns might limit the therapeutic range of this drug. Computational models that aid in balancing efficacy and toxicity would be of great help. Parametrizing models is difficult because the prodrug remdesivir is metabolized to its active form (RDV-TP) upon cell entry, which complicates dose–activity relationships. Here, we employ a computational model that allows drug efficacy predictions based on the binding affinity of RDV-TP for its target polymerase in SARS-CoV-2. We identify an optimal infusion rate to maximize remdesivir efficacy. We also assess drug efficacy in suppressing both wild-type and resistant strains, and thereby describe a drug regimen that may select for resistance. Our results differ from predictions using prodrug dose–response curves (pseudo-ECs). We expect that reaching 90% inhibition (EC) is insufficient to suppress SARS-CoV-2 in the lungs. While standard dosing mildly inhibits viral polymerase and therefore likely reduces morbidity, we also expect selection for resistant mutants for most realistic parameter ranges. To increase efficacy and safeguard against resistance, we recommend more clinical trials with dosing regimens that substantially increase the levels of RDV-TP and/or pair remdesivir with companion antivirals.

Exploring New Scaffolds for the Dual Inhibition of HIV-1 RT Polymerase and Ribonuclease Associated Functions.

Current therapeutic protocols for the treatment of HIV infection consist of the combination of diverse anti-retroviral drugs in order to reduce the selection of resistant mutants and to allow for the use of lower doses of each single agent to reduce toxicity. However, avoiding drugs interactions and patient compliance are issues not fully accomplished so far. Pursuing on our investigation on potential anti HIV multi-target agents we have designed and synthesized a small library of biphenylhydrazo 4-arylthiazoles derivatives and evaluated to investigate the ability of the new derivatives to simultaneously inhibit both associated functions of HIV reverse transcriptase. All compounds were active towards the two functions, although at different concentrations. The substitution pattern on the biphenyl moiety appears relevant to determine the activity. In particular, compound 2-{3-[(2-{4-[4-(hydroxynitroso)phenyl]-1,3-thiazol-2-yl} hydrazin-1-ylidene) methyl]-4-methoxyphenyl} benzamide bromide (EMAC2063) was the most potent towards RNaseH (IC50 = 4.5 mM)- and RDDP (IC50 = 8.0 mM) HIV RT-associated functions.

Consensus Recommendations Based on Evidence for Abdominal Sepsis in the Pediatric and Adult Population of Colombia

Intra-abdominal infections are frequent at all levels of health care, therefore, it is necessary to maintain a high level of clinical suspicion, performing the fastest and most cost-effective measures to confirm the diagnosis and offer a precise and targeted multidisciplinary therapy, this being the only way to have an impact on the morbidity of this infection, reducing mortality and minimizing the complications and costs of health care. Intra-abdominal infections are linked to the appearance and selection of resistant mutants in both bacteria and fungi, becoming currently a major public health problem. Increasing bacterial resistance when associated with a greater possibility of difficulties in antimicrobial treatment increases mortality. This evidence-based consensus brings together the recommendations for the diagnosis and treatment of intra-abdominal infections in the pediatric and adult population. With strict monitoring of bacterial resistance and stimulating the control of the risk factors that have the greatest impact on the appearance of this phenomenon, this consensus is intended to be a practical guide that is easy to implement, and with periodic updates it will favor and facilitate multidisciplinary and the adequacy of the therapeutic management of intra-abdominal infections.

A Leucyl-tRNA Synthetase Inhibitor with Broad-Spectrum Anti-Mycobacterial Activity.

Global infections by non-tuberculous mycobacteria (NTM) are steadily rising. New drugs are needed to treat NTM infections, but the NTM drug pipeline remains poorly populated and focused on repurposing or reformulating approved antibiotics. We sought to accelerate de novo NTM drug discovery by testing advanced compounds with established activity against Mycobacterium tuberculosis 3-aminomethyl 4-halogen benzoxaboroles, a novel class of leucyl-tRNA synthetase inhibitors, were recently discovered as active against M. tuberculosis Here, we report that the benzoxaborole EC/11770 is not only a potent anti-tubercular agent but is active against the M. abscessus and M. avium complexes. Focusing on M. abscessus, which causes the most difficult-to-cure NTM disease, we show that EC/11770 retained potency against drug-tolerant biofilms in vitro and was effective in a mouse lung infection model. Resistant mutant selection experiments showed a low frequency of resistance and confirmed leucyl-tRNA synthetase as the target. This work establishes the benzoxaborole EC/11770 as a novel preclinical candidate for the treatment of NTM lung disease and tuberculosis and validates leucyl-tRNA synthetase as an attractive target for the development of broad-spectrum anti-mycobacterials.

Identification of 16S rRNA mutations in Mycoplasma genitalium potentially associated with tetracycline resistance in vivo but not selected in vitro in M. genitalium and Chlamydia trachomatis.

Tetracyclines are widely used for the treatment of bacterial sexually transmitted infections (STIs) and recently have been used successfully for post-exposure prophylaxis of STIs in MSM. We investigated the in vitro and in vivo development of tetracycline resistance in Chlamydia trachomatis and Mycoplasma genitalium and evaluated 16S rRNA mutations associated with acquired resistance in other bacteria. In vitro selection of resistant mutants of reference strains of C. trachomatis and M. genitalium was undertaken by serial passage in medium containing subinhibitory concentrations of tetracycline or doxycycline, respectively. The 16S rRNA gene of the two microorganisms was amplified and sequenced at different passages, as were those of 43 C. trachomatis- and 106 M. genitalium-positive specimens collected in France from 2013 to 2019. No tetracycline- or doxycycline-resistant strains of C. trachomatis and M. genitalium, respectively, were obtained after 30 serial passages. The tetracycline and doxycycline MICs were unchanged and analysis of the 16S rRNA gene, the molecular target of tetracyclines, of C. trachomatis and M. genitalium revealed no mutation. No mutation in the 16S rRNA gene was detected in C. trachomatis-positive specimens. However, six M. genitalium-positive specimens harboured a mutation potentially associated with tetracycline resistance without known prior tetracycline treatment for patients. Tetracyclines did not select in vitro-resistant mutants of C. trachomatis or M. genitalium. However, 16S rRNA mutations either responsible for or associated with tetracycline resistance in other bacteria, including mycoplasma species, were identified in several M. genitalium-positive specimens.